US 9,811,073 B2
Machine tool with thermal displacement correction
Takuma Nishimura, Yamanashi (JP)
Assigned to FANUC CORPORATION, Yamanashi (JP)
Filed by FANUC Corporation, Yamanashi (JP)
Filed on Jun. 23, 2014, as Appl. No. 14/312,101.
Claims priority of application No. 2013-131684 (JP), filed on Jun. 24, 2013.
Prior Publication US 2014/0379117 A1, Dec. 25, 2014
Int. Cl. G05B 19/40 (2006.01); G05B 19/404 (2006.01)
CPC G05B 19/404 (2013.01) [G05B 2219/37405 (2013.01); G05B 2219/49219 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A numerical control machine tool with a thermal displacement correction, comprising:
a table;
a main shaft;
a main shaft straight line movement shaft configured to move the main shaft provided with a tool;
two or more table straight line movement shafts configured to move the table;
a numeric value control device for controlling the main shaft straight line movement shaft and the table straight line movement shafts,
the numerical control machine tool further comprising:
a main shaft motor;
a shaft load measuring unit configured to measure a load of the main shaft motor for driving the main shaft straight line movement shaft;
a reference contact time storage unit configured to store a time, from when the main shaft starts to move and time measurement begins at a predetermined position where the tool is not in contact with a work arranged on the table, to when the load of the main shaft motor measured by the shaft load measuring unit exceeds a predetermined value to be determined that the tool contacts the work, as a reference contact time;
an actual contact time storage unit configured to store a time, from when the main shaft starts to move and time measurement begins at a predetermined position where the tool is not in contact with the work arranged on the table, to when the load of the main shaft motor measured by the shaft load measuring unit exceeds the predetermined value to be determined that the tool contacts the work in machining after the reference contact time, as an actual contact time;
a thermal displacement calculation unit configured to calculate thermal displacement by multiplying a feed speed of the main shaft by a time difference between the reference contact time and the actual contact time when the time difference exceeds a predetermined time; and
a thermal displacement correction unit configured to correct a movement amount of the main shaft straight line movement shaft, based on the thermal displacement calculated by the thermal displacement calculation unit.